Dispensing Apparatus

ABSTRACT

A hand-held multi-dose dispensing apparatus ( 10 ) comprising a metering chamber ( 20 ) having an axis ( 21 ), an end portion ( 22 ) at one axial end of the chamber ( 20 ) and a side body portion ( 23 ) extending from the axial end portion ( 22 ), a piston arrangement ( 30 ) movable with a piston stroke along the axis of the metering chamber ( 20 ) with a seal portion ( 34 ) of the piston arrangement ( 30 ) being slidably engageable with an inside surface of a side portion ( 23 ) of the metering chamber, an inlet ( 27 ) for fluid to enter the metering chamber ( 20 ), and an outlet ( 31, 32 ) for fluid to be dispensed from the metering chamber ( 20 ), wherein the inlet ( 27 ) is provided on the side body portion ( 23 ) of the metering chamber and, in use, during a first portion of the piston stroke, the inlet ( 27 ) is in fluid communication with the metering chamber ( 20 ) and during a second portion of the piston stroke, the seal portion ( 34 ) of the piston arrangement ( 30 ) blocks the inlet ( 27 ) preventing fluid from passing from the inlet ( 27 ) into the metering chamber ( 20 ). This dispensing apparatus ( 10 ) reduces variations in the shot weight dispensed, by the metering of the fluid commencing at the point at which the piston enters the second portion of its stroke blocking off the inlet.

The present invention relates to a dispensing apparatus particularly amulti-dose dispensing apparatus for dispensing metered quantities offluid.

Conventional multi-dose dispensers have a metering chamber with a pistonarranged therein. The metering chamber draws the fluid to be dispensedfrom a reservoir through a dip tube. The dip tube is connected to thebase of the metering chamber via a one-way valve. When fluid is to bedispensed, the piston is depressed axially within the metering chamberto force the fluid from the chamber through an outlet. As pressure isapplied to the fluid in the metering chamber the one-way valve whichusually comprises a ball or rubber flap, seals the passage from themetering chamber to the dip tube. After the fluid has been dispensed,the piston is released and returns to its original rest position drawingmore fluid from the reservoir, up the dip tube, through the one-wayvalve in the base of the metering chamber and into the metering chamberas it rises.

However, the one-way valves are known to be inefficient and contributeto variations in the shot weight dispensed. Furthermore, the shot weightdispensed by different dispensers is found to vary due to the tolerancestack-up of a number of mass-produced components which cause differencesin the rest position of the pistons.

It is an object of the present invention to reduce variations in theshot weight of a multi-dose dispenser.

According to the present invention there is provided a hand-heldmulti-dose dispensing apparatus comprising

a metering chamber having an axis, an end portion at one axial end ofthe chamber and a side body portion extending from the axial endportion,

a piston arrangement movable with a piston stroke along the axis of themetering chamber with a seal portion of the piston arrangement beingslidably engageable with a side portion of the metering chamber,

an inlet for fluid to enter the metering chamber, and

an outlet for fluid to be dispensed from the metering chamber,

wherein the inlet is provided on the side body portion of the meteringchamber and, in use, during a first portion of the piston stroke theinlet is in fluid communication with the metering chamber and during asecond portion of the piston stroke the seal portion of the pistonarrangement blocks the inlet preventing fluid from passing from theinlet into or out of the metering chamber.

The positioning of the inlet on the side portion of the metering chamberand the action of the piston to respectively provide fluid communicationand block the inlet to the metering chamber during first and secondportions of the piston stroke eliminates the need for a one-way valve,reducing costs and increasing reliability of the dispenser. Furthermore,since the volume of fluid dispensed is determined by the point at whichthe piston enters the second portion of it's stroke as it blocks off theinlet and prevents further fluid from entering the metering chamber, amore consistent volume of fluid is dispensed. This eliminates variationsproduced by tolerance stack-up of dispenser components causing the restposition of the piston and thus the shot weight to vary betweendispensers.

A resilient member is preferably provided between the end portion of themetering chamber and the piston. The resilient member urges the pistoninto a rest position at the furthest point in its stroke from the endportion of the metering chamber. The resilient member may be an elasticmember or a spring for example. When activating the dispensingapparatus, a user preferably pushes the piston from its rest position,through the first portion of its stroke to the second portion at whichthe inlet is blocked, preventing further fluid from entering themetering chamber. As the piston progresses further into the secondportion of its stroke, fluid is forced out of the metering chamberthrough the outlet to be dispensed until the piston bottoms out. Afterthe piston has bottomed out, the user releases the piston and theresilient member urges the piston back to its rest position. As thepiston travels back through the second portion of its stroke with theinlet blocked, the pressure within the expanding metering chamber isreduced. When the piston reaches the first portion of it's stroke withthe inlet in fluid communication with the metering chamber, fluid issucked into the metering chamber by the reduced pressure therein and thepiston is urged into its rest position by the resilient member ready forthe next actuation.

The piston arrangement preferably comprises a first portion and a pistonseal, the piston seal being arranged to slidably engage and seal againstthe inside surface of the metering chamber and to be moveable relativeto the first portion of the piston arrangement, such that during asecond portion of the piston stroke when the pressure in the meteringchamber exceeds a particular level, the first portion and the pistonseal move relative to each other to open an outlet for fluid to bedispensed.

Embodiments of the present invention will now be described, by way ofexample only, with reference to the accompanying drawings, in which:

FIG. 1 shows a cross-sectional view of a dispensing apparatus with thepiston in the rest position;

FIG. 2 shows the cross-sectional view of the dispensing apparatus ofFIG. 1 with a piston arrangement blocking an inlet and

FIG. 3 shows the cross-sectional view of the dispensing apparatus ofFIG. 1 with the piston arrangement in the bottomed out position.

FIG. 1 shows a cross-sectional view of a dispensing apparatus 10 priorto actuation. The dispensing apparatus 10 has a metering chamber 20 withan axis 21, an end portion 22 at one end and a side body portion 23extending therefrom surrounding the metering chamber 20. In thisexample, the side body portion 23 has a narrower section 24 adjacent theend portion 22 then a frusto-conical portion 25 leading to a widersection 26. However, the metering chamber could be any desired shapesuch as cylindrical for example.

The side body portion 23 has an inlet 27 formed therein. In use, theinlet 27 is connected via collar 28 to a dip tube to draw fluid to bedispensed from a reservoir (not shown). The reservoir could be anysuitable container which is preferably, but need not be attached to thedispensing apparatus 10.

A piston arrangement 30 is provided inside the metering chamber 20. Thepiston arrangement comprises an insert rod 31 with an annular core 32slid over a portion of its length. The core 32 rests on a first annularseat 33 extending out from the insert rod 31. The piston arrangementalso has a piston seal 34 slid over the core 32. An outer surface of thepiston seal 34 slidably engages and seals against the inside surface ofthe side body portion 23 of the metering chamber 20. The piston seal 34rests on a second annular seat 35 which, like the first annular seat 33,also extends out from insert rod 31. A resilient member, in this examplea spring 36, is provided between an annular seat 37 on the core 32 andthe piston seal 34 to urge the piston seal 34 on to the annular seat 35on the insert rod 31.

A further resilient member, in this example another spring 38, isprovided between the end portion 22 of the metering chamber and anannular seat 39 on the underside of insert rod 31 to urge the pistonarrangement 30 into the rest position shown in FIG. 1 with an annularprojection 40 of the core 32 engaging a cap 50 provided on the meteringchamber 20. An upper section of the core 32 extends through a circularaperture 51 provided in the cap 50.

An appropriate actuator (not shown) is attached to the upper section ofthe core which extends through the aperture 51 provided in the cap 50.The actuator will be adapted for the application to which the dispensingapparatus is to be put, such as a nasal dispenser or oral dispenser forexample.

A ferrule 60 is provided attached to the cap 50. In use a container offluid to be dispensed (not shown) may be attached to the ferrule 60 sothat the metering chamber 20 is surrounded by the container and fluid tobe dispensed may be drawn from the container up a dip tube (not shown)connected to the inlet 27.

FIG. 2 shows the dispensing apparatus 10 beginning to be actuated withthe upper section of the core 32 which extends out through the cap 50being manually depressed by a user to push it towards the end portion 22of the metering chamber 20. As a user depresses the core 32, the annularprojection 40 disengages the cap 50 and the piston seal 34 slidesdownwards over the inside surface of the metering chamber to block theinlet 27 preventing further fluid from entering the metering chamber 20.Metering of the fluid commences once the piston seal 34 blocks the inlet27 as it is pushed downwards. As the volume of fluid dispensed iscontrolled by only one dimension of the metering chamber 20, i.e. thebottom of the inlet 27 to the end portion 22 of the metering chamber 20,shot weight variance is significantly reduced.

As the core 32 is pushed further towards the end portion 22 of themetering chamber 20, the pressure within the metering chamber 20increases. When the pressure within the metering chamber 20 overcomesthe force generated by the spring 36 acting on the piston seal 34, thepiston seal 34 unseats relative to the insert rod 31. In this examplethe pressure within the metering chamber 20 which causes the piston seal34 to unseat relative to the insert rod 31 is set at a predeterminedlevel by selection of a suitable spring 36. However, by selection of asuitable spring the piston seal 34 can be arranged to unseat relative tothe insert rod 31 at any desired pressure within the metering chamber20. Fluid from the metering chamber 20 is forced through openings (notshown) exposed in the lower portion of the core 32 by the unseating ofthe seal 34 from the insert rod 31 and up through the core 32 to anoutlet in the actuator.

Fluid continues to be dispensed as the core 32 is manually pressedfurther into the metering chamber 20 until the piston arrangementbottoms out. At this point a user stops pushing down the actuator andcore 32 and the spring 38 pushes the piston arrangement 30 back up themetering chamber 20. As the piston arrangement 30 passes through thisportion of its stroke, the piston seal 34 keeps the inlet 27 blocked andthe pressure within the metering chamber 20 reduces as its volumeexpands. When the piston seal 34 rises such that the inlet 27 is influid communication with the metering chamber 20, the reduced pressurewithin the metering chamber 20 draws fluid from the reservoir and diptube (not shown) into the metering chamber ready for the next actuation.The piston arrangement 30 is urged by spring 38 back into the restposition shown in FIG. 1 with the annular projection 40 of the overmoulded core 32 engaging the cap 50 ready for the next actuation.

The dispensing apparatus could be used to dispense any suitable fluid.However, the fluid is preferably a pharmaceutical product and mayinclude, for example, a pure drug or a drug with a liquid and/orpharmaceutical acceptable excipient.

Many variations may be made to the example described above whilst stillfalling within the scope of the invention. For example the meteringchamber 20 could be any suitable shape. Furthermore fluid could bepassed out of the metering chamber through any suitable outlet. Thedispensing apparatus is preferably made from a plastics material butcould be made from any suitable material. Furthermore any closure systemcould be used to attach the dispensing apparatus to a container of fluidto be dispensed such as a screw-on or snap closure.

1. A hand-held multi-dose dispensing apparatus comprising a meteringchamber having an axis, and end portion at one axial end of the chamberand a side body portion extending from the axial end portion, a pistonarrangement movable with a piston stroke along the axis of the meteringchamber with a seal portion of the piston arrangement being slidablyengageable with an inside surface of a side portion of the meteringchamber, an inlet for fluid to enter the metering chamber, and an outletfor fluid to be dispensed from the metering chamber, wherein the inletis provided on the side body portion of the metering chamber and, inuse, during a first portion of the piston stroke, the inlet is in fluidcommunication with the metering chamber and during a second portion ofthe piston stroke, the seal portion of the piston arrangement blocks theinlet preventing fluid from passing from the inlet into or out of themetering chamber.
 2. An apparatus according to claim 1, wherein aresilient means is provided between the piston arrangement and the endportion of the chamber.
 3. An apparatus according to claim 2, whereinthe resilient means is a spring.
 4. An apparatus according to claim 1,wherein the inlet is connectable to a reservoir of fluid to bedispensed.
 5. An apparatus according to claim 4, wherein the reservoirof fluid is a container attachable to the dispensing apparatus.
 6. Anapparatus according to claim 1, wherein the piston arrangement comprisesa first portion and a piston seal, the piston seal being arranged toslidably engage and seal against the inside surface of the meteringchamber and to be movable relative to the first portion of the pistonarrangement, such that during a second portion of the piston stroke whenthe pressure in the metering chamber exceeds a particular level, thefirst portion and the piston seal move relative to each other to open anoutlet for fluid to be dispensed.
 7. An apparatus according to claim 1,wherein during a second portion of the piston stroke with the pistonarrangement moving away from the end portion of the metering chamber andwith the seal portion of the piston arrangement blocking the inlet, thepressure within the metering chamber reduces until the first portion ofthe piston stroke is reached in which the inlet is in fluidcommunication with the metering chamber and the reduced pressure withinthe metering chamber draws fluid into the metering chamber ready for thenext actuation.
 8. (canceled)